This brief but important letter notifies a customer that he or she has overpaid you. It can serve as a very good customer relations letter.These strategies and this sample complaint letter can help you get your money back or reach another resolution. It's just an extra step we're taking to verify the returns we process and make sure refunds go to the right person. The salary overpayment resulted because . Many times when a third-party payer mistakenly pays a dental provider, the payer will request a refund of the overpaid amount.